i just disagree with his policies. >> reporter: and mitt romney said he is confident ryan will have a strong performance. >> i think paul ryan will do great. thank you. >> reporter: in an exclusive interview with diane sawyer, the president talked about what he expects from joe biden. >> what's your message to joe biden about tomorrow night? >> you know, i think joe just needs to be joe. >> reporter: biden scored points in his last debate four years ago, in what turned out to be the most-watched vice presidential debate in history. >> the notion that somehow because i'm a man, i don't know what it's like to raise two kids alone. i don't know what it's like to have a child you're not sure is going to make it -- i understand. i understand. >> emotional moment four years ago, jon. the audience could top that audience tonight. and it's coming as we're getting new, solid polls from the key battleground states of virginia, florida and ohio. >> reporter: yeah. this is the key thing. we've seen a national polls, romney has gained on the president in some cases. actually moved ahead of the pre